The present invention relates generally to incubators and more particularly to incubators having heaters and blowers for circulating warm air within the incubator, and even more particularly to controlling the speed of the motor driving the blower in response to the stability of the temperature of an infant within the incubator.
It is known to control the temperature of the air adjacent an infant in an incubator. It is also known to circulate the air within an incubator with a blower driven by a motor and to vary the blower speed based on the temperature of the air within the incubator. Thermistors for sensing air temperature and motor controllers are known and have been used to control the temperature of the air adjacent an infant in an incubator by controlling the output of the heater and by controlling the speed at which air is passed by the heater prior to infusion into an incubator hood. It is also known to attach transducers to infants in an incubator to directly measure the infants temperature.
Lessard et al., U.S. Pat. No. 5,730,355, discloses an incubator that increases the blower motor speed, and also the heater power, upon receiving a signal from a sensor indicating that an access panel has been opened. The duration of the increased blower motor speed (and heater power) is dependent at least in part on signals indicative of the infant skin temperature.
It has been found that when air is circulated within an incubator, the air flow over the infant increases evaporation losses. However, a certain amount of airflow is required in an incubator to evacuate carbon dioxide and replenish the oxygen content with outside air. It has also been found that motor and blower noise can be disruptive to infants. Reduction of the blower speed under certain circumstances to a level sufficient to maintain proper oxygen and carbon dioxide content of the air in the hood, would reduce evaporation losses and disruptive noise.
An infant incubator with a warm air circulation system including a heater and a motor driven blower controlled by an adaptive motor controller is disclosed. The disclosed control system reduces evaporative losses and blower noise while maintaining sufficient air flow for oxygen replenishment and carbon dioxide evacuation. The control system includes one or more sensors for determining the temperature of the infant and systems providing an output indicative of the stability of that temperature and a speed controller for the blower motor. The speed controller is operatively connected to the one or more temperature sensors to vary the speed of the blower motor dependent upon the stability of the temperature of the infant. Thus, the blower motor speed is determined at least in part by the stability of the temperature of the infant.
According to one aspect of the disclosure, an infant care unit has a platform upon which an infant rests, a canopy over the infant providing an enclosure with a controlled environment for the infant, an air circulation system having a heater and a blower driven by a blower motor to circulate warm air in the enclosure, and a control system for the air circulation system. The control system includes one or more sensors for determining the stability of the temperature of the infant and providing an output indicative of that temperature, and a speed controller for the blower motor. The speed controller is operatively connected to the one or more temperature sensors to vary the speed of the blower motor dependent upon the stability of the temperature of the infant. Thus, blower motor speed is determined at least in part by the stability of the temperature of the infant.
According to another aspect of the disclosure, adaptive motor speed controller for an incubator for an infant comprises one or more sensors for determining the stability of the temperature of the infant. The blower speed controller is responsive at least in part to the output of the one or more sensors to vary the blower speed and thereby vary the circulation of air in the incubator.
According to yet another aspect of the disclosure, a method for varying the blower speed of an incubator air circulation system of the type comprising a blower motor and a motor speed control circuit is disclosed. The method comprises the steps of sensing the stability of the temperature of an infant within the incubator and controlling the speed of the blower motor based at least in part on the stability of the temperature of the infant.
According to a further aspect of the disclosure, a control system is disclosed for controlling the volume of fluid circulated within an incubator carrying an infant. The control system comprises a temperature sensor and fluid control circuitry. The temperature sensor is positioned to sense the stability of the temperature of the infant and provide a temperature signal in response thereto. The fluid flow circuitry is operatively coupled to the temperature sensor and is configured to establish the volume of fluid circulated within the incubator in response to the temperature signal.
An incubator for an infant is disclosed according to another aspect of the disclosure. The incubator comprises a platform, a canopy, a sensor, and a blower assembly. The platform carries the infant and cooperates with the canopy to define a chamber receiving the infant. The sensor is positioned to sense the stability of the temperature of the infant and provide a temperature signal in response thereto. The blower assembly includes a fan, a motor, and a controller. The motor operates the fan to circulate air within the incubator. The controller is operatively coupled to the motor and to the sensor and establishes the speed of the motor and the speed of the fan in response to the temperature signal.
Additional features of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of a preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.